Multi-component cartridge and its application

ABSTRACT

Two-chamber cartridges for dispensing viscous pastes in which at least one of the chambers has a target break point that does not lie on the surface, of a common wall between the chambers.

The invention has to do with multi-component cartridges, in particular two-chambered cartridges for dispensing viscous pastes.

In the dental market motor-driven appliances for discharging and mixing two-component pastes are widespread. In them either double cartridges or tubular bags with backup cartridges are utilized. The products that are discharged from these cartridges as a rule are highly viscous pastes. For that reason they require high pressure in order to be able to flow through the mixer upstream. Accordingly the devices generate high power.

Since these cartridges/tubular bags are handling chemically curing substances, there is the possibility that the outlet channels close due to clogging formation. Should that occur only with one of the two components, then all the delivery pressure develops exclusively in this clogged chamber.

With the common devices here about 90 bars of pressure and more can build up.

Due to the geometric structural conditions of the devices the maximum wall strengths of the cartridge chambers are limited. The use of a cartridge that can withstand over 90 bars of pressure, however, does not constitute any guaranteed reliability, because most of the devices do not have a force limiter.

It is difficult to find a plastic material that is compatible with the content products and at the same time bears up against these great mechanical demands. Tested plastics that are compatible with the given pastes withstand about 60 bars of pressure at the most. Whenever the cartridges burst the contents in certain circumstances spray off several meters.

Since at present it does not seem possible to avoid bursting in every case and the devices are widespread, it is desirable to avoid the spraying off and to indicate to the users that the conveying process does not occur properly.

For that reason the problem arises of avoiding the effects connected with the bursting of multi-component cartridges (uncontrollable spraying off of the cartridge contents).

The problem is resolved in accordance with claim 1. Other advantageous details are described in the following claims.

There are cartridges on the market that for other construction reasons have wall reinforcement tapers and preferentially burst at these places.

But these tapers are at those places that give the user no security. They have no separate hollow spaces or partition walls.

The invention thus has to do with two-chambered cartridges for dispensing viscous pastes, in which at least one of the chambers has a target break point that does not lie on a surface, as the case may be, in common with the chambers. The target break point(s) open(s) necessarily into a hollow space outside of the chambers. Preferred are cartridges without a common separation wall between the chambers.

In case of bursting a spray guard in the sense of the invention at hand prevents spraying, i.e., that upon bursting of a multi-component cartridge an uncontrolled spaying out is avoided.

Such cartridges, e.g., are described and depicted in DE 100 22 160 A1.

By means of the drawing the invention is elucidated in more depth:

FIG. 1 shows a cross section traversing a two-chambered cartridge system of the state of the art technology with a common separation wall.

FIG. 2 shows a cross section traversing a two-chambered cartridge system, in which a partition wall links the cartridges and the target break point 12 is designed as a taper of the wall.

FIG. 3 shows a cross section traversing a two-chambered cartridge system, in which a partition wall links the cartridges and the target break point 13 is designed as a notch.

With double cartridges 1 having a common separation wall 2 the target break point can be shaped in such a way that a unilateral excess pressure, e.g., in the chamber 3 by ripping of the separation wall 2 can release tension into the other chamber 4 (FIG. 1). That is not foreseen with the invention at hand. The target break point does not lie on a surface in common with the chambers.

In a special design form (FIG. 2) the mixing wave 5 for driving the dynamic mixer runs between both the cartridge chambers 6, 7. A target break point can be planned, e.g., at the point 12. Material can escape into a hollow space formed in any way (space 9) that is closed in FIG. 2 by the space 14.

With many press-out devices the cartridge is free on all sides when in use. For this reason the “excess pressure” valve described above is shaped in such a way that material being sprayed out is collected in the hollow space 9.

This hollow space 9 is created in the design form depicted in the FIGS. 2 and 3 by introducing a partition wall 10 (preferably out of plastic) above the mixing wave running between the chambers 6, 7. Above that outside on the chamber wall 11 a taper 12, 13 running along the chamber wall 11 is introduced as a target break point. This can, e.g., be shaped as a radius flat portion 12 or as a notch 13.

While the outer diameters of both of the cartridge chambers 6, 7 tangentially 14 are linked by means of a surface (e.g., a label, a sheet or another wall), a hollow space 9 arises above the target break point 12, 13.

The partition wall 10 running between the chambers 6, 7 can:

-   -   be linked with both walls 11, 15 of chambers 6,7,     -   be linked only with one of both the walls 11, 15 of the chambers         6, 7,     -   be linked only with the wall 15 of the larger chamber 7 or be     -   a separate spare part that has no fixed link to the walls 11, 15         of the chambers.

Since the cartridge is designed in an additional preferred design form for a mixing ratio of 5:1, the pressure in the individual chambers with equal force on the pistons is variably great.

Therefore it suffices only to plan the target break point in this ratio for the smaller chamber. But even in such a case it can be advantageous to plan a target break point on each of the chambers in order to protect both the chambers.

Since in the present case double cartridges are being dealt with, in which both of the chambers are arranged pipe-shaped with a small spacing between each other, a hollow space can be created with this invention that captures the material spraying out when bursting. This principle can be applied to the double cartridges that are emptied manually, by air pressure or by motor. 

1. Two-chamber cartridge for dispensing viscous pastes, comprising a spray guard, and a target break point on at least one of said chambers.
 2. Two-chamber cartridge according to claim 1, wherein the target break point does not lie on a surface common to the two chambers.
 3. Two-chamber cartridge according to claim 1 or 2, wherein the target break point(s) open(s) into a hollow space (9) outside the chambers.
 4. Two-chamber cartridge according to claim 1 or 2 having no common separation wall between the chambers.
 5. Two-chamber cartridge according to claim 3, wherein the hollow space (9) is formed by A) a partition wall running between the chambers, B) the chamber walls and C) a further partition wall.
 6. Two-chamber cartridge according to claim 5 or 13, wherein said further partition wall is formed of a plastic wall, a sheet or a label.
 7. Two-chamber cartridge according to claim 1, wherein the target break point(s) is (are) designed as a notch or wall taper.
 8. Two-chamber cartridge according to claim 1, wherein each of said two chambers has a target break point.
 9. Two-chamber cartridge according to claim 5 or 13, wherein the partition wall running between the chambers is linked with the walls of both of the chambers.
 10. Two-chamber cartridge according to claim 5 or 13, wherein the partition wall running between the chambers is linked with the wall of one of the chambers.
 11. Two-chamber cartridge according to claim 10, wherein one chamber is larger than the other and the partition wall running between the chambers is linked only with the wall of the larger chamber.
 12. Two-chamber cartridge according to claim 5 or 13, wherein the partition wall running between the chambers is a spare part that has no fixed link to the wall of either of the chambers
 13. Two-chamber cartridge according to claim 4, wherein the hollow space (9) is formed by A) a partition wall running between the chambers, B) the chamber walls and C) a further partition wall. 